Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$148.64	10.725%	$164.5816	$164.58	$164.60	$164.60
Purchase #2	$86.43	13.809%	$98.3651	$98.37	$98.35	$98.40
Purchase #3	$17.41	10.281%	$19.1999	$19.20	$19.20	$19.20
Purchase #4	$97.69	11.188%	$108.6196	$108.62	$108.60	$108.60
Purchase #5	$148.98	9.383%	$162.9588	$162.96	$162.95	$163.00
Purchase #6	$72.42	6.176%	$76.8927	$76.89	$76.90	$76.90
Purchase #7	$118.87	10.462%	$131.3062	$131.31	$131.30	$131.30
7 purchase totals =	$690.44		$761.9239	$761.93	$761.90	$762.00